I think you may be right but i dont think this is the main reason. The fuel pipe does look a little too wide for the nipple, check it to see if the pipe is still fully flexible at the end check that the everything is fully tightened (fuel nipple).

Everything should realy be checked after each use as they do take a good hammering and the single cylinder engine bouncing up and down anything up to 500 times per SECOND causes even the tightest threads to come loose.